The present invention is related to cooling of electronic equipment, and more particularly to cooling electronics components.
Demand for higher performance supercomputers continues to create challenging thermal and packaging design environments for today""s computer packaging engineers. As the performance of CRAY supercomputers continues to grow exponentially, in general agreement with Moore""s law (Bar-Cohen, et al, 1988), the thermal and packaging solutions continue to become more complex.
The increase of supercomputer performance over the last 30 years was initially achieved with an increase in the complexity of the computer""s CPU by increasing the number of ICs within a CPU. The next step in performance was achieved by adding more gates per IC along with increasing the clock rate. Performance was further increased by the paralleling of CPUs and then the scaling of groups of CPUs. Now in order to continue on the path of Moore""s law, we are again pushing the IC technology and ultimately the performance of each individual CPU.
One technology that hasn""t been able to keep pace with the ICs is the printed circuit board (PCB) technology. The demands for component placement and IC net routings have exceeded the current state of the art in PCB technology.
One solution to this problem implements a multi-chip module with thin film routing layers (MCM-D) for the packaging of these high performance chip sets. This high density packaging design is, however, capable of producing heat fluxes on the ICs and MCM that approach values of 50 and 15 W/cm2, respectively. The control of the IC""s junction temperature is important for its reliability and for the performance of two communicating devices. The amount of induced leakage xe2x80x9cnoisexe2x80x9d that exists on an integrated circuit is also a function of its temperature.
A number of cooling methodologies have been described by Bar-Cohen (Bar-Cohen, A., xe2x80x9cThermal Management of Electronic Components with Dielectric Liquidsxe2x80x9d, JSME International Journal, Series B, vol. 36, No1,1993), by Simons (Simons, R. E., xe2x80x9cBibliography of Heat Transfer in Electronic Equipmentxe2x80x9d, 1989, IBM Corporation), by Incropera (Incropera, F. P., xe2x80x9cConvection Heat Transfer in Electronic Equipment Coolingxe2x80x9d, Journal of Heat Transfer, Nov. 1988, Vol. 110/1097) and by Bergles (Bergles, A. E., xe2x80x9cLiquid Cooling for Electronic Equipmentxe2x80x9d, International Symposium on Cooling Technology for Electronic Equipment, March 1987). Studies by Chu and Chrysler (Chu, R. C., and Chrysler, G. M., xe2x80x9cElectronic Module Coolability Analysisxe2x80x9d, EEP-Vol. 19-2, Advances in Electronic Packaging-1997 Volume 2, ASME 1997) and by Nakayama (Nakayama, W., xe2x80x9cLiquid-Cooling of Electronic Equipment: Where Does It Offer Viable Solutions?xe2x80x9d, EEP-Vol. 19-2, Advances in Electronic Packaging-1997 Volume 2, ASME 1997), however, indicate that these approaches are no longer capable of satisfying todays high density packaging requirements (Chu and Chrysler, 1997), (Nakayama, 1997).
As heat flux continues to increase, the most promising methods are those that utilize direct liquid cooling with dielectric fluids. Direct liquid cooling circumvents the problems of high thermal interface resistance associated with conventional technologies and is capable of providing very high heat transfer rates (Bar-Cohen, 1993). A number of such direct liquid cooling techniques are described in, xe2x80x9cThermal Management of Multichip Modules with Evaporative Spray Cooling,xe2x80x9d by G. W. Pautsch and A. Bar-Cohen, published in ASME Advances in Electronic Packaging 1999, EEP-Vol.26-2, 1453-1463, the discussion of which is incorporated herein by reference. That paper concluded that the method of choice for cooling high heat flux electronic components is describe as xe2x80x9cHigh Density, Pressure-Atomized Evaporative Spray Coolingxe2x80x9d. This condition occurs when a fluid is sprayed on a surface at a rate that maintains a continuously wetted surface, whose temperature is less than 25xc2x0 C. above the saturation temperature of the thermal coolant. This method, with the selection of an appropriate fluid, such as Fluorinert(trademark) FC-72 which has a boiling point of 56xc2x0 C. at standard atmospheric conditions, allows one to maintain high heat flux components at operating temperatures below 85xc2x0 C.
Each of the above cooling approaches has its deficiencies. What is needed is a system and method for cooling electronics components that addresses these deficiencies.
To address the problems stated above, and to solve other problems which will become apparent in reading the specification and claims, a system and method for cooling electronic components is described herein.
In one embodiment, an enclosure is provided which includes a plurality of a first set of electronic components, cooling means for cooling a gas, and distribution means for directing the gas across the electronics components and the cooling means, where the distribution means forms a closed system limiting the transfer of the gas both into and out of the distribution means.
Several options for the enclosure are as follows. For instance, in one option, the cooling means includes a cooling coil and means for directing water through the cooling coil. In another option, the enclosure further includes means for spray evaporative cooling a second set of electronic components. In yet another option, the first set of electronic components are low power components and the second set of electronic components are high power components.
In yet another embodiment, a system includes a chassis including one or more modules with a plurality of electronic components, where the chassis forms a closed system therein. The system further includes a gas distribution member positioned within the chassis, where the gas distribution member is configured to direct a chilled gas toward the electronic components. A gas cooling device is positioned within the chassis, where the gas cooling device is configured to cool the gas after the gas has been heated by the electronic components.
Several options for the system are as follows. For instance, in one option, at least one of the modules includes a mechanical subsystem having multiple electronic modules and at least one fluid conditioning unit, and optionally at least one of the modules includes a spray evaporative cooling assembly. In yet another option, the gas cooling device includes a heat exchanger.
In another embodiment, a system includes a chassis including one or more modules with one or more electronic modules and at least one fluid conditioning unit, where at least one of the electronic modules includes at least one spray evaporative cooling assembly. The system further includes a gas distribution member positioned within the chassis, where the gas distribution member configured to direct a chilled gas toward the electronic components. The system further includes a gas cooling device positioned within the chassis, where the gas cooling device configured to cool the gas after the gas has been heated by the electronic components.
Several options for the system are as follows. For instance, in one option, the at least one spray evaporative cooling assembly and the at least one fluid conditioning unit form a closed system. In another option, the chassis forms a closed system therein. In yet another option, the at least one fluid conditioning unit includes at least one pump and a heat exchanger. The spray evaporative cooling assembly, in another option, includes a fluid charged with a non-corrosive, inert gas, for example Nitrogen.
A method of cooling an electronics enclosure is provided in another embodiment. The method includes forcing air over a first set of electronic components and cooling the first set of electronic components, heating a liquid to a temperature near its boiling point, directing the heated liquid against a second set of electronic components where at least portion of the heated liquid vaporizes, drawing the vapor and the heated liquid away from the electronics components, condensing the vapor back into liquid, and cooling the air and recirculating the air through the enclosure, where the air is maintained within the enclosure in a closed system.
Several options for the method are as follows. For example, in one option, the method further includes recirculating the liquid, where the liquid and vapor are maintained within the enclosure in a closed system. In another option, the method further includes filtering the liquid, or charging the liquid with a non-corrosive gas. In another option, directing the heated liquid against the second set of electronic components includes directing the heated liquid against electronic components having a higher power than the first set of electronic components.
In yet another embodiment, a method of cooling an electronics enclosure having a plurality of electronics components includes directing a gas over electronic components and cooling the first set of electronic components, cooling the gas within the electronics enclosure, and recirculating the gas within the enclosure, where the air is maintained within the enclosure in a closed system.
Several options for the method are as follows. For instance, in one embodiment, cooling the gas includes passing the gas through a water cooled heat exchanger. Optionally, recirculating the gas includes directing the gas up sides of the enclosure to air plenums at the top of the enclosure. The method further optionally includes funneling the gas across heatsinks thermally coupled with the electronic components.
These and other embodiments, aspects, advantages, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the following description referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by the system, apparatus, procedures, and combinations particularly pointed out in the appended claims and their equivalents.